The present invention relates generally to high intensity lamps, and more particularly, to a high intensity discharge RF driven lamp for vehicles that produces low levels of electromagnetic interference (EMI).
The assignee of the present invention develops high intensity discharge headlamps for vehicles, and the like. Currently developed RF driven high intensity discharge lamps have a problem relating to the production of electromagnetic interference. RF power required to drive the lamps can exceed 100 watts at frequencies around 200 MHz. The desired radiated emissions specification for the high intensity discharge lamps exceeds FCC part 15 specifications by more than 20 dB. This means that EMI containment must provide more than 100 dB of isolation (with respect to the power generated by the RF power supply). This problem is aggravated by the fact that the lamp used in the currently developed lighting systems exposed so that light can efficiently provide illumination. The exposed lamp has a large RF voltage across its terminals. Because the currently developed lamp generates high RF and EMI levels, it is possible that such levels could inadvertently deploy vehicle airbags when the lamps are turned on, or interfere with other systems in the vehicle such as cellular phones, radios, or braking systems, and the like.
Accordingly, it is an objective of the present invention to provide for improved high intensity discharge RF driven headlight for use in vehicles, and the like, that produces low levels of electromagnetic interference (EMI).